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    Subject[PATCH 5.4 006/111] ubifs: fix wrong use of crypto_shash_descsize()
    Date
    From: Eric Biggers <ebiggers@google.com>

    [ Upstream commit 3c3c32f85b6cc05e5db78693457deff03ac0f434 ]

    crypto_shash_descsize() returns the size of the shash_desc context
    needed to compute the hash, not the size of the hash itself.

    crypto_shash_digestsize() would be correct, or alternatively using
    c->hash_len and c->hmac_desc_len which already store the correct values.
    But actually it's simpler to just use stack arrays, so do that instead.

    Fixes: 49525e5eecca ("ubifs: Add helper functions for authentication support")
    Fixes: da8ef65f9573 ("ubifs: Authenticate replayed journal")
    Cc: <stable@vger.kernel.org> # v4.20+
    Cc: Sascha Hauer <s.hauer@pengutronix.de>
    Signed-off-by: Eric Biggers <ebiggers@google.com>
    Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
    Signed-off-by: Richard Weinberger <richard@nod.at>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/ubifs/auth.c | 17 ++++-------------
    fs/ubifs/replay.c | 13 ++-----------
    2 files changed, 6 insertions(+), 24 deletions(-)

    diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
    index 8cdbd53d780c..f985a3fbbb36 100644
    --- a/fs/ubifs/auth.c
    +++ b/fs/ubifs/auth.c
    @@ -79,13 +79,9 @@ int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,
    struct shash_desc *inhash)
    {
    struct ubifs_auth_node *auth = node;
    - u8 *hash;
    + u8 hash[UBIFS_HASH_ARR_SZ];
    int err;

    - hash = kmalloc(crypto_shash_descsize(c->hash_tfm), GFP_NOFS);
    - if (!hash)
    - return -ENOMEM;
    -
    {
    SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);

    @@ -94,21 +90,16 @@ int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,

    err = crypto_shash_final(hash_desc, hash);
    if (err)
    - goto out;
    + return err;
    }

    err = ubifs_hash_calc_hmac(c, hash, auth->hmac);
    if (err)
    - goto out;
    + return err;

    auth->ch.node_type = UBIFS_AUTH_NODE;
    ubifs_prepare_node(c, auth, ubifs_auth_node_sz(c), 0);
    -
    - err = 0;
    -out:
    - kfree(hash);
    -
    - return err;
    + return 0;
    }

    static struct shash_desc *ubifs_get_desc(const struct ubifs_info *c,
    diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
    index b28ac4dfb407..01fcf7975047 100644
    --- a/fs/ubifs/replay.c
    +++ b/fs/ubifs/replay.c
    @@ -601,18 +601,12 @@ static int authenticate_sleb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
    struct ubifs_scan_node *snod;
    int n_nodes = 0;
    int err;
    - u8 *hash, *hmac;
    + u8 hash[UBIFS_HASH_ARR_SZ];
    + u8 hmac[UBIFS_HMAC_ARR_SZ];

    if (!ubifs_authenticated(c))
    return sleb->nodes_cnt;

    - hash = kmalloc(crypto_shash_descsize(c->hash_tfm), GFP_NOFS);
    - hmac = kmalloc(c->hmac_desc_len, GFP_NOFS);
    - if (!hash || !hmac) {
    - err = -ENOMEM;
    - goto out;
    - }
    -
    list_for_each_entry(snod, &sleb->nodes, list) {

    n_nodes++;
    @@ -662,9 +656,6 @@ static int authenticate_sleb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
    err = 0;
    }
    out:
    - kfree(hash);
    - kfree(hmac);
    -
    return err ? err : n_nodes - n_not_auth;
    }

    --
    2.25.1


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